Electron tube for high frequency



2 sheets-sheet 1 G. T. HOWES ELECTRON TUBE FOR HIGH-FREQUENCY Oct. 19,1948.

Filed Feb. 24, 1945 n quency operation.

Patented O'ct. 19, 1948 ELECTRON TUBE FOR HIGH FREQUENCY Gordon T.Howes, Belmont, Calif., assignor to Eitel-McCullough, Inc., San Bruno,Calif., a corporation of California i Application February 24, 1945,Serial No. 579,668

` (Cl. Z50-2.7.5)

9 Claims. 1

My invention relates to a tube having an external anode particularlyadapted for high fre- It is among the broad objects of my invention toprovide an improved envelope and terminal structure, and improved meansfor conductively supporting the electrodes within the envelope.

Another object is to provide an improved concentric stem structure for-a cathode.

Another object is to provide a better mounting and terminal structurefor a grid.

A further object is to provide an improved cooler for the anode.

The invention possesses other objects and features of advantage, some ofwhich, with the foregoing, will be set forth in the followingdescription of my invention, It is to be understood that I do not limitmyself to this; disclosure of species of my invention as I may adoptvariant embodiments thereof within the scope of the claims.

Referring to the drawings:

vFigure 1 is an axial sectional view of a tube embodying theimprovements of my invention, this view being about three times actualsize, taken in a plane indicated by line I-I of Figure 2.

Figure 2 is an end view looking at the grid terminal; and

Figure 3 is a fragmentary-sectional view showing a modied grid support.

In terms of broad inclusion, my tube comprises an envelope having anintermediate metallic anode section and vitreous end sections. A cathodestem with inner and outer stem members is arranged at one end of theenvelope for supporting the cathode, and a grid terminal member isarranged at the opposite end for supporting the grid. An improvedsealing means is provided between the cathode stem members, and animproved structure is provided for mounting the grid on its terminalmember. Improvements are also incorporated in .the cooler for the anode.

In greater detail, and referring to Figures 1 and 2, my tube comprisesan envelope having a tubular metallic anode section 2 with ared ends 3sealed to envelope sections 4 and 6 of vitreous material such as glass.Section 4 carries an exhaust tubulation which is sealed oil at tip 1after the envelope is evacuated.

A cathode stem is arranged at one end of the envelope comprising anouter tubular metallic stem member 8 and a solid inner metallic stem ymember 9. These stem members are concentric and both are coaxial withanode 2, the outer member 8 being sealed to vitreous section l of theenvelope. With a concentric stem arrangerclosure means comprising ametallic sleeve II interposed between the stem members, the lower-inturned end of the sleeve being sealed to the inner stem rod 9 by lavitreous bead I2 and the upper end being secured to the outer stem tube8 as by brazing I3 at the rims.

The stem is preferably assembled by rst securing sleeve II to rod 9 atsealing bead I2, which permits inspection and checking this joint forleaks before placement of these parts in stem tube 8. These parts arethen inserted in tubular member 8 and the final joint is made by brazingat I3. Since the braze is at the end of the outer tubular member thisjoint is also located for easy inspection.

The cathode is preferably of the indirectly heated type comprising acup-shaped cylindrical body I4 having a suitable emissive surface suchas an oxide coating on the cylindrical wall. These oxide coatings arewell known, and any of the usual compositions may be used. The lower endof metal body I4--is preferably closed by apertured plate I6, and thebody unit is supported on outer stem member 8 by bracket rods I1. Theheater for the cathode comprises a resistance coil I8 having its lowerend secured to inner stem member 9 and its upper end secured to body Ilby ear I9. This entire cathode and stem structure is inserted into theenvelope and sealed in place as a unit.

The grid is of generally tubular or cylindrical construction interposedbetween the cathode and anode, and preferably comprises longitudinalmetal bars 2| secured at one end as by welding or brazing to ring 22 andat the other end to the metal supporting cup 23. This cup is secured toa metallic terminal member 24 by a screw 2G. A

' iiange 21 on terminal 24'is sealed to a reentrant This three-4 piececooler structure enables it to be assembled about the intermediate anodeeven though the anode is smaller in diameter than the end portions ofthe tube. The cooler pieces are preferably secured together and to theanode, as by d soldering, to form an integral unit. Ii desired, iins maybe provided on ring dior increased radiation.

Figure 3 shows a modified structure adapted for more strenuous operationby providing a more l@ direct and better thermal path for conducting'heat away from the grid. This modiication also constitutes a simplerand more rigid support for the grid. It comprises an internallyextending supporting flange 32 formed integrally with ter 1g minalmember 2d. This one-piece stem structure is preferably of a metal havinggood thermal conductivity such as copper. The inner end of ange y 32 hasan annular groove formed between the :dange and a lip 33. Grid Wires 2iare engaged in 2@ this groove Vand are preferably held by deiorming lip33 inwardly under pressure to solidly grip to `Wires so that the latterare literally embedded in the copper. l. Such a joint is easy to make,has good mechanical strength, and provides an excellent thermal path forheat conduction. Ii desired, the ends of the grid wires may be otherwisesecured as by brazing into the retaining groove, vbut the coming thejoint is to form lip 33 as an annular outwardly extending iiange andthen forcing it downwardly and inwardly. against the grid wires by asuitable die. in this structure the lower lends of faces of achannel-shaped ring I claim: A

l. An electron tube comprising an envelope having a tubular metallicanode section anda vitreous section sealed to an end of the anode csection, a tubular metallic stem member sealed. to "said vitreoussection, an inner metallicstem member concentric with said tubularmember, vacuum-tight closure means interposed between the stem members,and a cathode within the envelopeA connected to said stem members.

' 2. An electron tube comprising an envelope having a tubular metallicanode section and al vitreous section sealed to an end of the anode'.section, a tubular metallic stem member sealed to said vitreous section,an inner metallic stem member concentric with said tubular member,.vacuum-tight closure means interposed between the stem members, acathode cylinder within the envelope, and a heater within the cylinderconnected to said stem members.

. 3. An electron tube comprising an envelope` having a tubular metallicanode section and a vitreous section sealed to an end of" the anodesection, a tubular metallic stem member sealed to G0 said vitreoussection, an inner metallic stem mem" ber concentric with said tubularmember, vacuum-tight closure means interposed between thestem members, acathode cylinder within the envelope supported on said tubular stemmember and a heater within the cylinder connected'at one end to theinner stem member and at the. other end to said cylinder.

4. An electron tube comprising an envelope, a tubular metallic stemmember secured to the envelope, an inner metallic stem member concentricwith said tubular member, a metallic sleeve interposed between andsecured to one of said y e@ members, a vitreous bead sealed to the otherend of the sleeve and to said other member, and an electrode in theenvelope connected to said stem members.

5. An electron tube comprising an envelope, a tubular metallic stemmember secured to the envelope, an inner metallic 'stem memberconcentric with said tubular member, a metallic sleeve interposedbetween. the stem members and secured at one end to the tubular member,a Vitreous bead sealed'to the other end oi? the sleeve and to said innermember, and an electrode in the envelope connected to said stem members.

6. Anelectron tube comprising an envelope having a tubular metallicanode section and a vitreous section sealed to an end of the anodesection, a tubular metallic stem member sealed to said vitreous section,an inner metallic stem Ymember concentric with said tubular member,

a metallic sleeve interposed between and secured to 'one of saidmembers, a vitreous bead sealed to the other end of the sleeve and tosaid other member, and any electrode in the envelope connected to saidstem members.

L 7. An electron tube comprising an envelope having a tubular metallicanode section and a vitreous section sealed to each end of the anodesection, atubular metallic stem member sealed to one of said vitreoussections, an inner metallic pression joint is preferred. A simple way ofmalr- 3@ stem member concentric with said tubular member, vacuum-tightclosure means interposed between the stem members, a cathode within theenvelope connected to saidI stem members, a

l metallic terminal member sealed to the other the grid wires arepreferably clamped between the 35' vitreous envelope section, and a gridin the envelope connected to said terminal member.

8. An electron tube comprising an envelope having a tubular metallicanode section and a vit ,reous section sealed to each end of the anodesection, a tubular metallic stem member sealed to one of said vitreoussections, an inner metallic stem` member concentric with said tubularmember, vacuum-tight closure means interposed between the stem members,a cathode within the envelope connected to and supported wholly by saidstem members, a metallic terminal member sealed to the other vitreousenvelope section, and a grid in the envelope connected to and supportedwholly by said'terminal member.

9. An electron tube comprising an envelope, a tubular metallic stemmember secured to the envelope, an inner metallic stem member concentricwith said tubular member, vacuum-tight closure means interposed betweensaid members, saidA closure means including a metallic sleeve projectinginto the tubular stem member and secured-at one end to said tubular stemmember, and an electrode in the envelope connected to said stem members.

GORDON lT. HOWES.

REFERENCES CIVITED '1 The following lreferences are of 'record in the leof this patent:

UNITED STATES PATENTS Number Name Date 1,814,376 Gebhard et al. July 14,1931 2,011,647 Mouromtsel et al. Aug. 20, 1935 2,128,232 Dallenbach Aug.30, 1938 2,163,589 y Dallenbach et al. June 27, 1939 2,368,031 LlewellynJan. 23, 1945

